1. Field of the Invention
The present invention relates to signal tracking. More particularly, the invention relates to a method and apparatus for signal tracking that utilizes a universal algorithm to determine a geolocation based on one or more signal measurements.
2. Description of the Related Art
The ability to determine the source geolocation of emitted signals is becoming increasingly important as the use of wireless communications devices becomes commonplace throughout the world. For example, the U.S. Federal Communications Commission Enhanced 911 (E911) rules will eventually require cellular telephone carriers to identify the geolocations, i.e. the physical source locations, of subscribers who place calls to 911. Additionally, wireless communication device users often desire to acquire accurate geolocations for navigation purposes, such as to generate a route between a current location and a destination. Further, military and law enforcement agencies often desire to locate sources of emitted signals for tracking and targeting purposes.
Methods and devices have been developed that enable signal geolocations to be determined. Some of these methods include utilizing Global Position System (GPS) elements that must be coupled with signal emitters to determine geolocations, thereby increasing system cost and complexity. Other methods include utilizing one or more collector elements, such as antennas, to generate signal measurements and compute geolocations utilizing the generated signal measurements.
Although utilizing signal measurements enables geolocations to be determined without physically interfacing with signal emitters, such methods generally require specific and static measurement types and are incompatible across multiple or varying platforms. For example, if a signal measurement system is configured to determine a geolocation utilizing an angle of arrival, it will be inoperable to utilize another signal measurement, such as a time difference of arrival, to determine the geolocation. Thus, signal measurement methods and related systems are often crippled due to configuration and/or system changes that affect available measurement types.
Additionally, developed signal measurement methods and related systems generally require at least a pair of measurements, such as both an angle of arrival and a frequency difference of arrival, to compute a geolocation. As a result, such methods and systems are unable to utilize a single measurement to accurately reflect a geolocation or utilize one or more measurements to accurately update a previously determined geolocation. Thus, the ability to accurately determine signal geolocations is often limited due to the lack of functionality of developed methods and systems.